There is a growing interest in tin-containing semiconductor materials like germanium tin (Ge1-xSnx) for many applications, such as, high mobility channel and strain engineering for advanced microelectronic devices, direct bandgap Group IV materials for photonic devices, or GeSn alloys for photovoltaic devices.
Monocrystalline germanium tin (Ge1-xSnx) semiconductor materials may be deposited or grown using a variety of techniques. For example, vacuum processes, including molecular beam epitaxy and chemical vapor deposition, may be used to form monocrystalline germanium tin (Ge1-xSnx) semiconductors.
In some semiconductor device applications, the germanium tin (Ge1-xSnx) semiconductor may be doped with select impurities to obtain a desired electrical conductivity. For example, the germanium tin (Ge1-xSnx) semiconductor may be doped p-type by the incorporation of boron into the germanium tin (Ge1-xSnx) semiconductor. However, in some applications it may be desirable to deposit or grow a germanium tin (Ge1-xSnx) semiconductor which not only has a high p-type doping concentration but also has a significant tin (Sn) composition. For example, for a germanium tin (Ge1-xSnx) semiconductor with a tin (Sn) composition greater than x=0.03, it may be difficult to obtain a doping concentration greater than 1×1020 dopants per cubic centimeter. Hence, there is a tradeoff between the tin (Sn) composition and the doping concentration when depositing or growing germanium tin (Ge1-xSnx) semiconductor materials. Accordingly, methods are desired for forming a germanium tin (Ge1-xSnx) semiconductor with significant tin (Sn) composition and a high doping concentration.